The present invention relates to a pole wheel which can be connected to a wheel hub of a motor vehicle having an annular collar which extends in the radial direction, forms an outer edge, and is provided with a large number of apertures which are arranged at substantially identical angular intervals from one another.
Pole wheels, also commonly referred to as exciter wheels or exciter rings for a wheel speed sensor, are used as functional parts of anti-lock braking systems (ABS) in motor vehicles, where they are usually fastened to the associated wheel hub of the motor vehicle in the attachment region of a disc brake.
In general, a disc brake assembly includes a brake disc, which is connected to the wheel hub and with which brake pads make contact in order to slow the motor vehicle. The braking operation is performed by the friction linings of the brake pads which bear against the brake disc.
In addition to the brake disc, the disc brake assembly includes a pole wheel which is fastened to the wheel hub in a rotationally fixed manner, and which is operatively connected to a sensor. A conventional pole wheel of this type is described, for example, in DE 102 05 046 A1 and DE 101 45 947 C1.
In order to transmit the braking torque to the wheel hub, the brake disc is also fastened to the wheel hub in a rotationally fixed manner, for example by using external toothed elements of the wheel hub corresponding to internal toothed elements of the brake disc, disposed in an interlocking manner.
To provide the required axial fixing of the brake disc, WO 97/48 919 A1 discloses providing a stop ring which firstly is firmly screwed to the wheel hub, and secondly bears against the brake disc. As a result, the wheel hub is substantially fixed in the axial direction. Some slight axial deflection may occur merely on account of the material-dependent elasticity of the stop ring.
In order to also prevent axial movement in one direction, DE 103 57 374 A1, which was published after the priority date of the present application, discloses a stop which is fixed in the direction of interest and against which the brake disc bears. In this case, separate components of the pole wheel are required, first for axially securing or restricting the movement of the brake disc on one side, and second for operation of said ABS.
The conventional design of pole wheels naturally leads to relatively high production and installation costs which stand in the way of optimizing the brake system.
The present invention, among other objectives, further develops pole wheels to improve their range of use and such that the associated disc brake can be produced in an overall more cost-effective manner.
According to the exemplary embodiments of the present invention, a pole wheel is provided which can be connected to a wheel hub of a motor vehicle. The pole wheel has an annular collar extending in the radial direction to form an outer edge which is provided with a large number of apertures arranged at a substantially identical angular distance from one another. According to the invention, a dimensionally stable stop is integrally formed directly or indirectly on the collar such that it rests on the brake disc in order to fix it in the axial direction, while the brake disc is connected to the wheel hub.
According to this exemplary structural configuration, the use of a separate axial securing means for the brake disc can be dispensed with in one direction. Instead, the function of axially securing the brake disc is also performed by the correspondingly modified pole wheel according to the invention.
On account of the multiple functions of the pole wheel, considerable advantages are obtained primarily in production and installation of the disc brake. In one embodiment, the collar of the pole wheel and the stop connected thereto are preferably integrally formed together. For example, the stop may have the form of a radially extending, circumferential element which extends substantially parallel to the collar, but in the opposite direction.
In this embodiment, the collar and the stop may be connected by a circumferential web which is at right angles to the latter. Alternatively, the circumferential web may be inclined, with the result that a substantially Z-shaped cross section is produced. It will be understood that in this context the web may be formed by a solid piece of material such as, for example, solid metal.
In one embodiment, one may produce the pole wheel as a stamped sheet-metal part, which results in particularly low-cost manufacture for the component.
In order to provide the stop with sufficient dimensional stability, said stop may, according to one advantageous embodiment of the invention, be provided with beads or embossed ribs. In another embodiment, it is possible to form a flange on the stop or to angle the stop at the free edge region in the same direction as the web, producing an approximate U-shaped section which is formed by the angled portion, the stop and the web.
It may be necessary to provide reinforcing elements such as those described above for increasing the dimensional stability of the stop because the collar with the apertures distributed over its circumference is, for manufacturing reasons, formed from a relatively thin metal sheet. For example, the sheet may have a thickness of about 2 mm. A sufficiently exact tooth system, which is formed by the apertures, can be produced more easily with thin metal sheets of this type.
According to a further advantageous embodiment of the invention, the entire Pole wheel is fastened to the wheel hub. For example, screws may be provided axially in relation to the wheel hub, and may be distributed over the circumference, preferably at substantially identical angular intervals. The screws are passed through the stop, and are fastened into the abovementioned hub teeth of the wheel hub which correspond to the toothed elements of the brake disc used to transmit torque.
The exemplary connection of the pole wheel comprising the collar and the stop to the wheel hub provides additional advantages over the known stop structures, since the connecting means are positioned outside of the brake disc. This configuration protects the connecting means from the intense heated generated during a braking operation, with the result that the risk of the screws becoming loose on account of being excessively heated is effectively reduced. Further advantageous embodiments of the invention will be described below.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.